My primary research is in the area of instrumentation for interferometric gravitational-wave observatories and laser-optical dark matter searches.
I was a member of the Interferometer Sensing and Control team and of the Input Optics Subsystem team for the Advanced LIGO observatories. Working at the interface between the main interferometer and the Input Optics, I was initially responsible for the requirement flow down from the core interferometer to the Input Optics and the pre-stabilized laser system. In addition to length and alignment sensing and control, I also studied thermo-optical problems associated with the very high laser power stored in each interferometer arm. I suggested changing the arm cavities from near plane-parallel to near confocal and moving the beam expanding telescopes into the power and signal recycling cavities to better confine the spatial eigenmodes inside the recycling cavities and improve the power handling capabilities of Advanced LIGO. These design changes were later adopted and my group provided the optical design of the entire interferometer. I also led the Input Optics – in many ways, the most diverse optical system of Advanced LIGO – through the final procurement, installation and commissioning phase. All this work contributed to the first direct detection of gravitational waves by Advanced LIGO. With the dawn of the Einstein Telescope in Europe and Cosmic Explorer in the US, I am again exploring how to contribute to the next generation of ground-based gravitational-wave observatories.
I am a member of the LISA consortium and co-chaired for many years the interferometry working group of the former LISA International Science Team until it was abandoned in 2012. The principles of the LISA interferometry which will now be implemented were developed during those years. My own group developed an electronic phase delay system that was capable of generating realistic LISA signals in a hardware-in-the-loop LISA simulator. This simulator was used to demonstrate Time Delay Interferometry, a key technology for LISA, and arm locking, a laser frequency stabilization technique which uses the ultra-stable LISA arms as a reference.
After the initial cancellation of LISA, I participated in feasibility studies at NASA and ESA, and, following the success of LISA Pathfinder and the detections by Advanced LIGO and Virgo, these studies had an enormous impact on the fast recovery of LISA. At UF, I expanded our dimensional stability studies where we continue to explore ways to build and characterize ultra-stable structures and joints for future use in LISA and as ground support equipment for LISA tests. Our current focus is on testing the dimensional stability of LISA telescope prototypes at the pm/rtHz level across the LISA operational temperature range and measure the effective coefficient of thermal expansion of the prototype. At the AEI, we plan to improve the stability of the structures and the sensitivity of our interferometric sensing systems by at least two orders of magnitude to pave the way for even more challenging space missions beyond LISA.
I am also the Co-spokesperson of the ALPS collaboration. ALPS is an experiment located at DESY to search for axion-like particles, their scalar counterparts, hidden-sector photons and other exotic beyond-the-standard-model interactions. These light shining through walls experiments use a feeble interaction between two photons and the hypothetical axion-like particle to turn light into axions and, behind an opaque wall, back into light. A discovery of such an interaction would be the first direct proof of beyond the standard model interactions and would almost certainly answer the question what constitutes the omnipresent dark matter.
Director at Max Planck Institute for Gravitational Physics
Head of the department Precision Interferometry and Fundamental Interactions
Professor of Physics, University of Florida
Feb. 1997: Ph.D., Physics, Universität Hannover
Apr. 1993: Diploma, Physics, Universität Hannover
Since August 2022: Director at Max Planck Institute for Gravitational Physics (Albert Einstein Institute), Hannover
Since August 2012: Professor, University of Florida
2007-2012: Associate Professor, University of Florida
2003-2007: Assistant Professor, University of Florida
2000-2003: Research Scientist, University of Florida
2001-2003: Visiting Scientist, GSFC-NASA
1998-2000: Postdoctoral Scholar, University of Florida
1997: JSPS-Postdoctoral Fellow, UEC
2016: Gruber Prize
2016: Special Breakthrough Prize
2016: Recognized by the UK Royal Astronomical Society
2014: APS Fellow
2006: International Educator of the Year Award (Junior Category), University of Florida
1997: JSPS-Postdoctoral Fellow
- Secretary of the Board of the LISA Consortium
- LISA Formulation Management Team
- ESA LISA System engineering office: Affiliated Member
- Lead of the heterodyne sensing and control system
- Co-Chair of the controls WG